The Polymerase Chain Reaction (PCR) technology has played an important role in biotechnology, and no technique which could replace the PCR technology has yet been developed. Accordingly, the PCR technology will continue to have an essential position in the field of biotechnology in the future.
In addition to the development of the PCR technique, the Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) technique which is a method of analyzing the gene expression based on the PCR technique was invented. The RT-PCR has a higher sensitivity in detection of a small amount of RNA molecule than a Northern blot analysis, a dot blot analysis, and a nuclease protection method, and is simpler than in situ hybridization. In particular, the RT-PCR is very useful in analyzing various samples in very small amounts, and therefore, the RT-PCR method is also widely used in clinical diagnosis.
Based on these advantages of the PCR and RT-PCR methods, many attempts have been made to combine the methods with high throughput and highly parallel method such as microarray. However, unlike the PCR or RT-PCR which is typically performed in a solution, the reactions which happen on a solid surface has many disadvantages to be overcome such as non-specific adsorption, steric hindrance and electrostatic interaction between biomolecules, etc. Specifically, when a high temperature condition is required like PCR or RT-PCR, the organic thin film coated on the surface has to show high thermal stability.
A Glass or gold substrate have generally been used as a solid support for immobilizing a biomolecule in a biosensor or a microarray, and they are coated with an organic layer which holds the biomolecule. However, because most of silane or thiol compounds forming the organic layer are attached onto these solid supports via Si—O or Au—S bond which is unstable in a buffer solution at a high temperature, it is difficult to hold the biomolecules on the substrate surface. Therefore, first of all, the thermal stability of the organic layer on the surface should be secured to perform PCR or RT-PCR on the surface using these solid supports.